Cylinder plug

The plug, “rotor” in Spanish, is the cylindrical part inside the lock cylinder that the key goes into and which turns when the key is the right one. It sits inside the housing, the fixed body, and when it turns it moves the cam that operates the lock.

Between plug and housing there are aligned holes where the pins sit. With the correct key, the gap between each pair of pins falls exactly on the shear line, the edge of the plug, and the plug can turn. With the wrong key, a pin crosses that line and blocks the turn.

The usual faults are dirt, dust or salt that slow the turn, wear after years of use or a piece of broken key stuck inside. If the key goes in but is hard to turn, do not force it, because that is how keys end up snapping.

If your cylinder is starting to feel stiff, send us a photo. Sometimes a clean is enough and sometimes a cylinder replacement is needed; if the key has already snapped, see our broken key extraction.